Mars, Here We Come!

6. Mars: The Specs

Here's a brief description of some of the physical parameters of Mars as compared to the Earth:

Property Mars Earth Ratio (Mars/Earth)
Mass 6.42 x 1023 kg 5.97 x 1024 kg .107
Diameter 6787 km 12456 km 0.533
Mean Density 3933 kg/m3 5520 kg/m2 0.713
Surface Gravity 3.69 m/s2 9.78 m/s2 0.377
Escape Velocity 5.03 km/s 11.19 km/s 0.450
Solar Irradiance 595 W/m2 1380 W/m2 0.431
Sidereal Orbit Period 686.98 Earth days 365.26 Earth Days 1.881
Orbit Eccentricity 0.0934 0.0167 5.593
Sidereal Rotation Period 24.6229 hours 23.9345 1.029
The surface air pressure is around 6.1 mb on average (as compared to 1 bar at the surface of the Earth). The average surface temperature is about 210 K (that's about -60 C). The atmosphere is (by volume): 95.32% Carbon Dioxide (CO2), 2.7% Nitrogen (N2), 1.6% Argon (Ar), 0.13% Oxygen (O2), 0.08% Carbon Monoxide (CO). By comparison, the Earth's atmosphere is 78% Nitrogen (N2), 21 percent Oxygen (O2), 1 percent Argon (A), with traces of water vapor and carbon dioxide.

Now lets look at some of the geological features of Mars!

Canyons and Volcanoes
This mosaic of Mars is similar to the view you would see from a spacecraft. The center of the scene shows the entire Valles Marineris canyon system, over 4000 km (2486 mi) long and up to 7 km (5 mi) deep. It extends from Noctis Labyrinthus, to the chaotic terrain on the east side. Many ancient river channels begin from the chaotic terrain and north-central canyons and run north. Three Tharsis volcanoes are visible to the west (dark red spots). They rise 10 to 18 km (6 to 11 mi) above the Tharsis Plateau, attaining elevations of 18 to 26 km (11 to 16 mi).

Valles Marineris
Nearly half of the Valles Marineris canyon system is visible here. The entire system extends over 4000 km (2490 mi), covering about one fifth the circumference of Mars. Some parts of the canyon run as deep as 7 km (4 mi) and5 as wide as 200 km (125 mi). Compared to Valles Marineris, the Grand Canyon on Earth seems quite small at 446 km (277 mi) long, 30 km (18 mi) wide and 1.6 km (1 mi) deep.

Olympus Mons
Olympus Mons is the largest volcano on Mars. This shield volcano, similar to volcanoes in Hawaii, measures 624 km (374 mi) in diameter by 25 km (16 mi) high. It is 100 times larger than Mauna Loa on Earth. Located on the Tharsis Plateau near the equator, Olympus Mons is bordered by an escarpment. The caldera in the center is 80 km (50 mi) wide and contains multiple circular, overlapping collapse craters created by different volcanic events. The radial features on the slopes of the volcano were formed by overflowing lava and debris.

The Southern Polar Cap
This mosaic of Viking Orbiter frames shows the South Polar Cap of Mars. The polar cap is composed of water and carbon dioxide ice. The ice appears reddish due to dust that has been incorporated into the cap.

The Surface and Color
This Viking Lander 2 site has stones which were probably ejecta from impact craters near the Lander 2 site. Many of the rocks are angular and are thought to be only slightly altered by the wind and other forms of erosion. Drifts of sand and dust are smaller and less noticeable at the Lander 2 site. The overall red coloring of the Martian terrain is due to the presence of oxidized iron in the regolith (dirt). The pink color of the sky is caused by extremely fine red dust that is suspended in Mars' thin atmosphere.

Goto Section 7 - Phobos and Deimos.